Technical Field
Exemplary embodiments of the present disclosure relate to an eco-friendly vehicle, and, particularly, to an on-board charger for an eco-friendly vehicle, which uses a detection circuit having high reliability of control pilot (CP) signals transmitted from electric vehicle supply equipment to the on-board charger, so as to be capable of achieving an improvement in performance and reductions in cost and size of the charger.
Description of Related Art
In general, an electric vehicle (EV) or a plug-in hybrid electric vehicle (PHEV) are considered eco-friendly vehicles and equipped with a charger power system for charging of traction batteries. Such a charger power system is connected to electric vehicle supply equipment (hereinafter, referred to as “EVSE”), and the EVSE is classified into a quick charger and a slow charging stand. The quick charger is configured in a manner to use direct current (DC) power and rapidly charge batteries by controlling a battery management system (hereinafter, referred to as “BMS”), whereas the slow charging stand is configured in a manner to use AC power and slowly charge batteries by control of the BMS and an on-board charger (hereinafter, referred to as “OBC”).
Typically, when batteries are charged under control of the OBC in a state in which the vehicle ignition is turned off, a connector of the EVSE is connected to a control circuit so that the control circuit is turned on. Meanwhile, the control circuit should be maintained in a turned-on state while the charge is performed. However, due to the J1772 standard, which is a charging standard, it is impossible to directly turn on the control circuit using provided signals. For this reason, control pilot (hereinafter, referred to as “CP”) signals transmitted from the EVSE to the charger are used to directly turn on the control circuit. However, since the CP signals are pulse-width modulation (PWM) signals, there is a limit to maintain a turned-on state directly using the signals.
For this reason, controlling the control circuit so it is turned on during charging of batteries uses a method (e.g., “first method”) of enabling signals by separately providing an always-operating CP detection circuit besides the control circuit, or a method (e.g., “second method”) of processing CP signals after an auxiliary power unit is turned on through initial input of the CP signals so as to continuously generate enable signals. However, the first method to control the control circuit so it is turned on during charging of batteries may be adversely affected by dark current. In addition, the second method is limited to uniformly generate output signals due to various conditions of the CP signals changed according to an input voltage range of 6 to 12V and a duty ratio of 5 to 95%. To this end, a smoothing circuit and/or amplifier circuit may be used, but problems arise in that a driving time of the circuit is limited, and the circuit has a likelihood of unstably operating.